This invention relates to a blow-molded bottle-shaped container of biaxially oriented synthetic resin such as polyethylene terephthalate resin.
Recently, bottle-shaped containers of relatively large size for containing liquids such as, for example, liquors or soy sauces have been widely utilized.
The most effective means for molding a bottle-shaped container of this type include means for molding the bottle-shaped container by biaxial orientation blow-molding a preformed piece molded from a synthetic resin material. Particularly, a blow-molded bottle-shaped container of biaxially oriented polyethylene terephthalate resin has a number of advantages such as light weight, excellent mechanical strength and physical properties, and inexpensive cost, together with the possibility of mass production.
Since the blow-molded bottle-shaped container of biaxially oriented synthetic resin of this type has a round configuration as a whole with a smooth surface and is molded in a relatively large size, the bottle-shaped container may tend to slip when held by hand, is accordingly inconvenient to be grasped by the hand, and must be associated with a grip separately molded as a holding means of the container body.
In order to obviate this difficulty of holding the conventional bottle-shaped container, axially slender recesses have been manufactured at both sides of a cylindrical body of the bottle-shaped container so as to utilize the rear halves of the container body as a grip.
The abovementioned conventional bottle-shaped container is certainly convenient to handle the container body by hand, but does not always have sufficient mechanical strength. More specifically, the conventional bottle-shaped container of this type exhibits a serious drawback that, when the conventional bottle-shaped container is dropped in the state that a predetermined quantity of liquid is filled in the container body to conduct a strength test. The slender recesses formed on the body of the bottle-shaped container are externally projected and deformed by the internal pressure of the liquid container in the container body by the dropping impact, resulting in no recovery of the deformation.
Further, this external projecting deformation of the recesses on the body of the conventional bottle-shaped container means insufficient buckling strength of the recesses formed on the container body, and this bottle-shaped container is desired to provide high mechanical strength.